The present invention relates to a terminal for an electrical connector, in particular, but not exclusively, a terminal formed on a pin of an electric plug.
In a conventional electric plug there are three pins, and electrical connecting wires or cables composed of a plurality of strands are connected thereto. In each of the earth, neutral, and live pins, the multi-strand cable is inserted into a circular cross-section channel of a terminal on top of the pin, and a screw threaded into the terminal is used to apply pressure on the cable by tightening the screw. Thus the screw presses the cable hard against the inner wall of the channel to provide connection between the pin terminal and the electric wire, so that the cable receives current from the power supply, through the pin. However a problem arises in that as the screw is tightened by rotating the screw by a screw driver, the tip of the screw first comes into contact with the bare cable, and a downward force and also a rotary force are applied to the cable. Since the cable is composed of a group of strands, some of the wire strands are caused to be deformed. It is an object of the present invention to overcome, or at least reduce, this problem.
According to the present invention there is provided a terminal for an electrical connector, the terminal comprising: a terminal body, an opening in the terminal body for receiving an electrical conductor, a screw threaded into the terminal body for securing the electrical conductor in the opening by applying pressure to the conductor by rotation of the screw, and a pressure transfer element positioned between the screw and the opening for applying pressure from the screw to a conductor in the opening to secure the conductor in the opening.
In one preferred form, one end of the terminal body has a cavity leading to the said opening for the electrical conductor, the transfer element being positioned in the cavity and being movable in the cavity towards the said opening to secure the electrical conductor in the opening, the walls of the cavity having screw threads to allow the screw to be threaded into the terminal body and to protrude into the cavity to make contact with the pressure transfer element. Conveniently the opening is a channel extending into or through the terminal body in one direction and the cavity is an open trough-shaped cavity on top of the terminal body extending transverse to direction of the channel. In one preferred form embodying the invention the pressure transfer element has one side for contacting a conductor in the said opening in the terminal body, and an opposite side for contacting the screw, the first side having a protruding portion for contacting the conductor in the opening, and the opposite side having a U-shaped valley therein into which the screw protrudes.
In one particularly preferred form the opening comprises a channel of circular cross-section, and the pressure transfer element has a convex curved surface on its side remote from the screw, positioned opposite an interior surface of the channel, for securing a conductor in the channel by gripping the conductor between the curved surface of the pressure transfer element and the interior surface of the channel. Preferably the convex curved surface has a part circular cross-section of radius less than the radius of the cross-section of the channel.
It is a preferred feature that the pressure transfer element is mounted in such a manner as to allow movement of the element towards the said opening for the conductor, but to prevent rotary movement of the transfer element relative to the said opening. Another preferred feature is that the contact area of the pressure transfer element available in use for contacting an electrical conductor in the opening, is greater than the contact area of the screw with the pressure transfer element. These preferred features allow the conductor to be secured in place while preventing, or reducing, the tendency for a rotation of the screw to deform the conductor which is being secured.